Unbeknownst to many, “garnet,” the January birthstone, does not refer to one type of stone, but a family of six different species of stone. Read on to learn more about these six types of garnet and their unique characteristics, and be sure to visit a local jeweler for more information.
Almandine and Pyrope
The garnet species almandine and pyrope are the most widely-used garnets in the gem industry. However, almandine’s most common variety is usually opaque and not typically used in gemstones. Only the less common, dark-red and transparent forms of almandine are used as gemstones. Pyrope is commonly used in gemstones due to its transparency and consistent lack of flaws or inclusions. Rhodolite, a variety of pyrope that comes colors varying from rose-red to violet is especially common and well-regarded in the gem industry.
Spessartite and Grossular
Spessartite is a type of garnet that is usually orange to orange-red in color. Spessartite stones often contain iron impurities while simultaneously possessing a high refractive index, giving them extra brilliance. With new deposits of spessartite recently exploited, the gem has grown in popularity in the gem trade.
Grossular is the most varicolored species of garnet. It can come in yellow, red, cinnamon, white, gray, and purple — to name a few — each different color due to a different type of iron impurity found in the stone. Grossular also has the notable variety tsavorite, which typically occurs in a brilliant green, and hessonite, which occurs in a yellow or yellow-green color.
Andradite and Uvavorite
Andradite is the most lustrous garnet species and naturally occurs in a number of forms, most of which are too opaque to be used in the gem trade. The more transparent “gemmy” andradite forms are thus highly coveted. Andradite is typically referred to by one of its three subspecies: demantoid, melanite, and topazolite.
Uvarovite is the rarest of the six species of garnets and is rarely found in crystals large enough for faceting. Uvavorite is unique in that it only comes in a single color: a deep green.
For more information on garnet, the January birthstone, visit a local jeweler or gemologist.